From 2279f2c62f1e5c0dfaa500e637c92d528acd85b1 Mon Sep 17 00:00:00 2001
From: Eugene Zhulenev <eugene.zhulenev@gmail.com>
Date: Thu, 8 Oct 2020 00:26:45 +0000
Subject: Use lgamma_r if it is available (update check for glibc 2.19+)

---
 .../Eigen/src/SpecialFunctions/SpecialFunctionsImpl.h  | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

(limited to 'unsupported')

diff --git a/unsupported/Eigen/src/SpecialFunctions/SpecialFunctionsImpl.h b/unsupported/Eigen/src/SpecialFunctions/SpecialFunctionsImpl.h
index 0044b8a27..c65f69a54 100644
--- a/unsupported/Eigen/src/SpecialFunctions/SpecialFunctionsImpl.h
+++ b/unsupported/Eigen/src/SpecialFunctions/SpecialFunctionsImpl.h
@@ -57,11 +57,23 @@ struct lgamma_retval {
 };
 
 #if EIGEN_HAS_C99_MATH
+// Since glibc 2.19
+#if defined(__GLIBC__) && ((__GLIBC__>=2 && __GLIBC_MINOR__ >= 19) || __GLIBC__>2) \
+ && (defined(_DEFAULT_SOURCE) || defined(_BSD_SOURCE) || defined(_SVID_SOURCE))
+#define HAS_LGAMMA_R
+#endif
+
+// Glibc versions before 2.19
+#if defined(__GLIBC__) && ((__GLIBC__==2 && __GLIBC_MINOR__ < 19) || __GLIBC__<2) \
+ && (defined(_BSD_SOURCE) || defined(_SVID_SOURCE))
+#define HAS_LGAMMA_R
+#endif
+
 template <>
 struct lgamma_impl<float> {
   EIGEN_DEVICE_FUNC
   static EIGEN_STRONG_INLINE float run(float x) {
-#if !defined(EIGEN_GPU_COMPILE_PHASE) && (defined(_BSD_SOURCE) || defined(_SVID_SOURCE)) && !defined(__APPLE__)
+#if !defined(EIGEN_GPU_COMPILE_PHASE) && defined (HAS_LGAMMA_R) && !defined(__APPLE__)
     int dummy;
     return ::lgammaf_r(x, &dummy);
 #elif defined(SYCL_DEVICE_ONLY)
@@ -76,7 +88,7 @@ template <>
 struct lgamma_impl<double> {
   EIGEN_DEVICE_FUNC
   static EIGEN_STRONG_INLINE double run(double x) {
-#if !defined(EIGEN_GPU_COMPILE_PHASE) && (defined(_BSD_SOURCE) || defined(_SVID_SOURCE)) && !defined(__APPLE__)
+#if !defined(EIGEN_GPU_COMPILE_PHASE) && defined(HAS_LGAMMA_R) && !defined(__APPLE__)
     int dummy;
     return ::lgamma_r(x, &dummy);
 #elif defined(SYCL_DEVICE_ONLY)
@@ -86,6 +98,8 @@ struct lgamma_impl<double> {
 #endif
   }
 };
+
+#undef HAS_LGAMMA_R
 #endif
 
 /****************************************************************************
-- 
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